As cases continue to accrue in different places we will hear more talk about quarantine and isolation. These are two terms that are frequently confused, which is too bad, because isolation makes sense for influenza and quarantine doesn’t. So what do they mean?
What quarantine and isolation have in common is they are both designed to interrupt the transmission of a disease that spreads from person to person. Quarantine is the legally enforceable segregation of people who people who have been or may have been exposed but who aren’t (yet) sick. Some people talk about “voluntary quarantines,” but it’s best to reserve the word for those instances where people are compelled to stay confined. If you took everyone who ha been in Mexico for the past week and involuntarily confined them to their residences or a holding facility, that would be a quarantine. It is a draconian measure and doesn’t work for flu and usually makes matters worse. People will intentionally attempt to evade quarantines and in the process spread the disease farther and faster. Historically, the more well off have had an easier time evading quarantines. Their record in interrupting transmission is often poor and they aren’t recommended for influenza.
Isolation, on the other hand, is the (usually uncoerced) segregation of people who are already sick. It makes a great deal of sense to prevent people who are definitely shedding virus to mingle with the general public. If you are sick, you should stay home or be in a hospital.
Either isolation or quarantine can be ordered or enforced by state and local authorities, but CDC also has authority to detain, medically examine or conditionally release persons suspected of having certain contagious diseases. To deal with bird flu, the list of contagious diseases was enlarged by Executive Order in 2005 to include “influenza caused by novel or reemergent influenza viruses that are causing, or have the potential to cause, a pandemic.” CDC also uses its quarantine authority to monitor disease at ports of entry to the US, and they are doing that now. Under this authority they may detain specific travelers until their health status is ascertained. While no general federal quarantines have been ordered since the 1918 influenza pandemic, and it isn’t likely one will be ordered this time at the federal level, there is a moderately large gray area when it comes to temporary detention. Rather than paraphrase, this is how CDC puts it:
Modern quarantine lasts only as long as necessary to protect the public by (1) providing public health care (such as immunization or drug treatment, as required) and (2) ensuring that quarantined persons do not infect others if they have been exposed to a contagious disease.
Modern quarantine is more likely to involve limited numbers of exposed persons in small areas than to involve large numbers of persons in whole neighborhoods or cities.
The duration and scope of quarantine measures would vary, depending on their purpose and what is known about the incubation period (how long it takes for symptoms to develop after exposure) of the disease-causing agent. Examples include:
A few hours for assessment.
Passengers on airplanes, trains or boats believed to be infected with or exposed to a dangerous contagious disease might be delayed for a few hours while health authorities determine the risk they pose to public health. Some passengers may be asked to provide contact information and then released while others who are ill are transported to where they can receive medical attention. There have been a few instances where state and local public health authorities have imposed a brief quarantine at a public gathering, such as a shelter, while investigating if one or more people may be ill.
Enough time to provide preventive treatment or other intervention.
If public health authorities determine that a passenger or passengers on airplanes, trains or boats are sick with a dangerous contagious disease, the other passengers may be quarantined in a designated facility where they may receive preventive treatment and have their health monitored.
For the duration of the incubation period.
If public health officials determine that one or more passenger on airplanes, trains or boats are infected with a contagious disease and that passengers sitting nearby may have had close contact with the infected passenger(s), those at risk might be quarantined in a designated facility, observed for signs of illness and cared for under isolation conditions if they become ill.
Quarantined individuals will be sheltered, fed and cared for at home, in a designated emergency facility or in a specialized hospital, depending on the disease and the available resources. They will also be among the first to receive all available medical interventions to prevent and control disease, including:
Early and rapid diagnostic testing and symptom monitoring.
Early treatment if symptoms appear.
Isolation would last for the period of communicability of the illness, which varies by disease and the availability of specific treatment. Usually it occurs at a hospital or other health care facility or in the person’s home. Typically, the ill person will have his or her own room and those who care for him or her will wear protective clothing and take other precautions, depending on the level of personal protection needed for the specific illness.
In most cases, isolation is voluntary; however, federal, state and local governments have the authority to require isolation of sick people to protect the public. (CDC)
CDC has rarely used its quarantine authority, and I don’t expect it to use it in this instance. But I wouldn’t rule out state and local authorities doing so out of fear.